CLASS DISCUSSION AND NOTES

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1 CLASS DISCUSSION AND NOTES April 2011 Mon Tue Wed Thu Fri AH-8 (individual) Chap. 12 XML AH-9 (team) Quiz #2

2 I. GETTING STARTED COURSE OVERVIEW II. DATABASE DESIGN & IMPLEMENTATION III. SELECTED TOPICS Introduction (C-1) Introduction to Structured Query Language (C-2) Rel. Model and Normalization (C-3) Database Design and Normalization (C-4) Data Modeling with the ER Model (C-5) Transforming Data Models into Database Designs (C-6) Managing Multiuser Databases (C-9) XML (C-12) SQL for Database Construction (C-7)

3 MODULE III: SELECTED TOPICS XML (Text: Chapter 12) NOTES FOR CLASS SESSION STARTING POINTS Questions to begin our deliberation 1. Why is there a confluence of database processing and document processing? 2. Why is it important to understand and learn XML? Student Learning Objectives (Desired Outcomes) At the end of in-class and outside-class work on this topic, you should be able to: 1. Explain the importance of XML. [Comprehension] 2. Explain the elements of XML, including XML documents, document type declarations (DTD), and XML style sheets. [Comprehension] 3. Explain the role of XSLT in materializing XML documents. [Comprehension] 4. Explain the basic concepts of XML Schema and understand their importance to database processing. [Comprehension]

4 5. Create XML documents from database data. [Application] QUESTIONS TO EXPLORE READINGS Q 1. Why is XML Schema likely to gain in importance? Q 2. What are the roles and relationships of XML documents, DTD files, XSLT, and XML stylesheets? In Class Exercise Set 9 (IC 9) Text Chapter 13: XML Points to consider (Please take time review all the points before starting the exercise): 1. Database processing and document processing need each other. a. Database processing needs document processing for transmitting database views. b. Document processing needs database processing for storing and manipulating data. 2. XML (extensible Markup Language) is a hybrid of document processing and database processing. a. It provides a standardized yet customizable way to describe the content of documents. b. XML documents can automatically be generated from database data, and vice versa. 3. Document Type Declarations (DTDs) and XML Schemas can be used to describe the content of XML documents.

5 4. XSLT, the Extensible Style Language, may be used to materialize (transform) an XML document (using an XSL document) from the XML document into HTML or into an XML in another format. 5. Some views cannot be created in a single SQL statement because the construct requires two or more multivalued paths. XML does not have this limitation. XML Tutorial (Quick-start guide) 1. XML is designed to store, retrieve and transport data. 2. XML tags are not pre-defined and you must define your own tags. 3. The rules for the tags can be defined with the help of Document Type Declarations (or) XML Schema. 4. XML is not platform specific (or) programming language specific. XML can be used in different operating systems like Linux, Windows, etc. XML APIs are available in Java,.NET, VB, etc. It is a W3C recommendation. 5. XML is not a programming language by itself. It is used by the programming languages to store, retrieve and transport data. It is just a human-readable and machine-readable way of representing the data. 6. The following is a sample of an XML document: <?xml version="1.0" encoding=" UTF-8"?> <bookstore> <book Id= 1 > <Title>Harry Potter</Title> <Author> J K Rowling</Author> </book>

6 <book Id= 2 > <Title>Lord of the Rings</Title> <Author> Tolkien</Author> </book> </bookstore> 7. The root element in the above document is <bookstore>. All <book> elements in the document are contained within <bookstore>. 8. The <book> element has an attribute called Id. 9. The <book> element has 2 children: <Title>, <Author>. 10. All XML elements must have a closing tag. XML tags are case sensitive. 11. XML elements must be properly nested. 12. XML documents must have a root element. 13. When the rules are followed, then the XML document is called a Well-formed XML document. 14. If you pay close attention to the above document, you will find similarities between a XML document and a database table. Table Name: bookstore Id Title Author 1 Harry Potter J K Rowling 2 Lord of the Rings Tolkien 15. The root element <bookstore> becomes the Table name. The child element <book> becomes a row in the table. 16. The child elements of book - <Title>, <Author> and the attribute Id became the columns of the table.

7 17. The above document is just an illustration. There can be a case where the root element becomes Database name. The various child elements of the root element becoming different tables and so on. <?xml version="1.0" encoding="utf-8"?> <User_Order> <User_Data> <User ID="U1"> <FirstName>Michael</FirstName> <LastName>Morgan</LastName> <Phone> </Phone> </User> <User ID="U2"> <FirstName>Eric</FirstName> <LastName>Schmidt</LastName> <Phone> </Phone> </User> </User_Data> <Order_Data> <Order ID="O1" ISBN="78906" User="U1"/> <Order ID="O2" ISBN="78906" User="U2"/> <Order ID="O3" ISBN="78907" User="U1"/> </Order_Data> </User_Order> 18. In the above document, <User_Order> is the database name. <User_Data> and <Order_Data> are the table names and so on. 19. A "Valid" XML document is a "Well Formed" XML document, which also conforms to the rules of a Document Type Definition (DTD) or XML Schema (XSD).

8 20. Consider the following DTD for the bookstore XML document: <?xml version="1.0" encoding="utf-8"?> <!ELEMENT bookstore (book*)> <!ELEMENT book (Title, Author)> <!ATTLIST book Id ID #REQUIRED > <!ELEMENT Title (#PCDATA)> <!ELEMENT Author (#PCDATA)> 21. <!ELEMENT bookstore (book*)> means that bookstore is an element and it can zero or more instances of other element called <book> as children. 22. <!ELEMENT book (Title, Author)> implies that book is an element and it has two other elements called <title> and <author> as children. <title> and <author> can occur only once with in <book>. 23. <!ATTLIST book Id ID #REQUIRED > implies that <book> element has an attribute called Id and it is a required attribute. It is of a data-type called ID (like Varchar, Int, etc., in a DBMS, XML has a data-type called ID. It can hold any type of value but it should be unique within a document) 24. <!ELEMENT title (#PCDATA)> <!ELEMENT author (#PCDATA)> implies that <title> and <author> are elements and they can hold a value of type PCDATA (equivalent of String in XML). 25. As you can see, the DTD specifies the guidelines for an XML document (like the element names, attributes of an

9 element, children of an element, data type of an element, minimum occurrence and maximum occurrence of an element). You can equate the DTD to the database schema. 26. A reference to a DTD document is specified in the XML document using the instruction - <!DOCTYPE bookstore SYSTEM "book.dtd"> just below <?xml version="1.0" encoding="utf-8"?>. Exercise Set 1. Let us consider the following XML document which represents data about different Racers. Please provide a corresponding table structure for the data represented. XML Document <?xml version="1.0" encoding="utf-8"?> <Racer_Data> <Racer Id="R1"> <FirstName>John</FirstName> <LastName>Smith</LastName> <Phone> </Phone> </Racer> <Racer Id="R2"> <FirstName>Brian</FirstName> <LastName>Schmidt</LastName> <Phone> </Phone> </Racer> </Racer_Data> 2. Consider the table structure provided below. Please provide a corresponding XML representation.

10 Table Name: RACE_DATA Id RaceName DateOccurred R1 Grand Prix I 01/01/09 R2 Grand Prix II 02/01/09 Take Home Assignment Set 9 (AH 9) Text Chapter 12: XML 1. Consider the following XML document which represents Order Data. Please provide the corresponding table structure. XML Document <?xml version="1.0" encoding="utf-8"?> <Order_Data> <Order Id="O1"> < ISBN>78906</ISBN> <User>Raj</User> <Quantity>10</Quantity> </Order> <Order Id="O2"> < ISBN>78909</ISBN> <User>Poorna</User> <Quantity>20</Quantity> </Order> </Order_Data> 2. In the case of Little John s online book store, describe a scenario where XML can be used.

CLASS DISCUSSION AND NOTES

Mon CLASS DISCUSSION AND NOTES October 2009 Tue Wed Thu Fri 19 20 21 22 23 AH-6; PBL & Project Peer Evaluations Chap. 7 SQL/DB Construction AH-6; PBL & Project Peer Evaluations Chap. 7 SQL/DB Construction